The present invention relates to electrolytic cells comprising polymeric film composition electrodes and separator membranes and to a method of economically making such cells. In particular, the invention relates to rechargeable lithium battery cells comprising an intermediate separator element containing an electrolyte solution through which lithium ions from a source electrode material move between cell electrodes during the charge/discharge cycles of the cell. The invention is particularly useful for making such cells in which the ion source electrode is a lithium compound or other material capable of intercalating lithium ions, and where the electrode separator membrane comprises a polymeric matrix made ionically conductive by the incorporation of an organic solution of a dissociable lithium salt which provides ionic mobility.
These flexible polymeric electrolytic cell separator membrane materials may be employed as separator elements with mechanically assembled battery cell components or in composite battery cells constructed of successively coated layers of electrode and electrolyte compositions. Preferably, however, electrolytic cells for use as rechargeable batteries are constructed of individual electrode and electrolyte composition membranes which are laminated together with outer layers of conductive metal foil serving as current collectors, typically under heat and pressure.
The present invention provides, in particular, a means of improving the adhesion between polymeric electrode membrane compositions and the collector elements during the lamination operation. Through the use of this improvement, the present electrolytic cell yields a more economical and reliable battery cell product.